I have a TiVO hooked to my Onkyo 805 to my Mits 73835 DLP. It looks pretty darn good on the HD channels. Then I switch on my PS3, likewise hooked up, put in a full on BD, like the Dark Knight, and remember why I spent all this money on kit.

There is no comparison, my ISO calibrated TV, with BD, all connected via HDMI, just knocks the socks off of anything else.

If your system doesn't, then it's time to get it properly calibrated (BTW, you did take the plasma off of burn in mode, didn't you...), check the leads, or head out for some new glasses.